In the disclosure of the present invention reference is mostly made to the treatment of diabetes by delivery of insulin, however, this is only an exemplary use of the present invention.
Drug Injection devices have greatly improved the lives of patients who must self-administer drugs and biological agents. Drug Injection devices may take many forms, including simple disposable devices that are little more than an ampoule with an injection means or they may be highly sophisticated electronically controlled instruments with numerous functions. Regardless of their form, they have proven to be great aids in assisting patients to self-administer injectable drugs and biological agents. They also greatly assist care givers in administering injectable medicines to those incapable of performing self-injections.
In particular pen-style injection devices have proven to provide an accurate, convenient, and often discrete, way to administer drugs and biological agents, such as insulin. Modern devices have become more sophisticated and often include diverse and robust functions, such as memories for remembering time and amount of last dose, as well as, in the case of insulin devices, blood glucose monitors. While pen-style injection devices are typically cylindrically shaped with a needle protruding from the most distal portion of one end of the device, some devices have other shapes with the needle no longer protruding from the most distal part of an end of the device, e.g. Innovo® and InnoLet® from Novo Nordisk A/S Bagsvaerd Denmark.
Typically, injection devices use a pre-filled cartridge containing the medication of interest, e.g. 1.5 or 3.0 ml of insulin or growth hormone. The cartridge is typically in the form of a generally cylindrical transparent ampoule with a needle pierceable septum at one end and an opposed piston designed to be moved by the dosing mechanism of the injection device. The injection devices generally are of two types: “Durable” devices and “disposable” devices. A durable device is designed to allow a user to replace one cartridge with another cartridge, typically a new cartridge in place of an empty cartridge. In contrast, a disposable device is provided with an integrated cartridge which cannot be replaced by the user; when the cartridge is empty the entire device is discarded. Most injection devices are provided with a releasable pen cap covering the cartridge and the needle mount portion (see below), this allowing the user to inspect the content of the cartridge by removing the cap.
Cartridge-based drug delivery devices are typically designed for use with replaceable subcutaneous needle assemblies allowing a user to mount a fresh and sterile needle before each subcutaneous injection, however, many users decide to use a needle assembly more than one time. To allow a needle assembly to be mounted in fluid communication with the cartridge through the needle-pierceable septum, the injection device is provided with a needle mount which may be formed either as part of the device or as part of the cartridge, see e.g. U.S. Pat. Nos. 5,693,027 and 6,126,646, which are hereby incorporated by reference.
A typical subcutaneous injection needle assembly designed for use with a drug delivery device comprises a fine needle mounted in a hub having coupling means allowing the hub to be mounted on the injection device, thereby introducing the distal end of the needle through the cartridge septum. The hub may be cup-shaped with the inner mounting means adapted to engage corresponding mounting means on the injection device, e.g. a threaded connection or a bayonet coupling as disclosed in US 2008/0015519. The needle is normally provided in a container having an opening sealed by a peelable membrane, the container being in releasable, e.g. frictional, engagement with the needle hub. The coupling between container and hub allows the container to be used as a mounting tool when the membrane has been peeled off, just as it can be used as a tool for removing the needle after use. To further protect the pointed distal end of the needle and prevent unintentional user contact with the needle a needle cap is mounted on the hub covering the distal end of the needle. The needle cap will normally be removed just prior to use and remounted just after. Indeed, in case a user decides to remove the needle assembly from the injection device after an injection the container can be mounted on the needle assembly without the needle cap being in place. As many users prefer to use a needle assembly more than once the cap is normally designed to house a needle assembly including the needle cap. Indeed, this feature also allows a user to mount a fresh needle assembly in advance.
As appears from the above, the mounting and use of disposable needle assemblies in connection with the use of drug delivery devices involves handling and keeping track of a number of members, e.g. the needle cap needs handling almost every time an injection is taking place. Further, to inspect the content of the cartridge or confirm that a needle is mounted a user has to remove the pen cap.
Having regard to the above, it is an object of the present invention to provide devices and methods allowing secure and easy operation of a drug delivery system comprising a drug delivery device with a reservoir and a thereto mountable needle assembly.